A child's imagination has no bounds. Some boys and girls pretend to be astronauts and mermaids. Others run alongside imaginary friends. But, for a few children around the world, the mind conjures hallucinations that never go away. At times, these make-believe visions even lead to violent behavior.

Michael and Susan Schofield know all too well how mental illness can affect a child's life. Their 7-year-old daughter, Jani, has been diagnosed with one of the most severe cases of childhood schizophrenia Jani's doctors say they've ever seen.

According to the National Institute of Mental Health, schizophrenia is a chronic, disabling brain disorder that may cause a person to hear voices and misinterpret reality. In some cases, schizophrenic patients believe people are plotting to harm them, which causes extreme agitation or depression.

Jani may be younger than most people with schizophrenia, but she battles the same demons. In her case, hallucinations take the form of imaginary children and animals. There's a little girl named 24 Hours, a rat named Wednesday, and a cat named 400 who tells her to do bad things.

Over the years, Michael, a college English professor, says he's met more than 200 different cats, rats, dogs, birds and little girls that only his daughter can see.